Hello,
I was racing in FL when the G5.7 came out in the early '80s. We did pretty well on their racing team in such places as Holland, Monterey, and Ft. Walton Beach.
We sailed double trap on a mast w/spreaders.
There was no mast rotation control, though making it difficult to control the sail to weather. Downwind we passed everyone in sight.
The 5.0 didn't have spreaders. Both used the H16 extrusion.
Hope this helps.